Sensitivity in GSM (Global System for Mobile communication) Base Transceiver Station (BTS) receivers is crucial since the power budget depends upon it. A typical, schematic GSM network is shown in FIG. 1. When considering the link budget for several networks, it is often seen that the uplink is the limiting link, e.g. from user equipment (UE) to base station (BTS). Consequently, it is typically the uplink that breaks first if a user moves to the boundary of a cell. Thus, improving the uplink will improve the cell coverage for most networks. This will lead to reduced number of sites needed to deploy and thus give savings from site rental and hardware.
The sensitivity of a receiver is limited by several factors, some of the most prominent include:                Thermal noise in the equipment (background noise, tower mounted amplifiers (TMA), feeders, radio unit receivers etc)        Spurious emission from other transmitters (mobile phones and other base stations)        Non-linearity that originates from strong interference sources.        
Most base transceiver stations covering macro cells use a concept of two-way-diversity to improve the uplink signal. This means that two separate antenna paths are used all the way from the antenna into the receiver; see FIG. 2. The signals from the two antenna branches are combined in the transceiver (receiver) and a sensitivity gain is obtained. This gain consists of two parts, a diversity gain, and a power gain:                The diversity gain is achieved because having two or more signals makes it possible to mitigate the adverse effects of fading.        The power gain stems from the fact that it is possible to coherently combine the signals in the receiver, thus increasing the signal to noise ratio (SNR). The improvement is theoretically 3 dB, although in practice there are always implementation losses.        
For GSM systems, a TRX (Transceiver) provides the radio gain path for one GSM carrier. GSM systems typically use a time-division multiplexing scheme in which each carrier is divided into 8 timeslots in the air. A TRX typically contains one transmitter and one receiver. The receiver can manage the above described 2-way diversity.
In a noise limited system, the receiver sensitivity in the uplink cannot, in any known manner, be improved without adding extra antennas, feeders or other hardware units to the site e.g. base transceiver station.